-lGL wasn't in the right spot for some systems?
Merge branch 'opengl' of https://github.com/hmaon/OpenXcom into opengl
fix software rendering.
Merge branch 'opengl' of github.com:hmaon/OpenXcom into opengl
add OpenGL files to cmake list, I guess?
Merge branch 'master' of https://github.com/SupSuper/OpenXcom into opengl
Merge pull request #324 from hmaon/opengl

compilation stuff for various esoteric build methods